vice president biden canceled a weekend event there as well. the first lady scrubbed a tuesday event in new hampshire due to possible bad weather. weather could become a factor in the final push for votes and if the effects linger, might even affect turnout on election day. that said, there are so many factors to consider, so much forecasting in the form of polling. there's new cnn/orc numbers tonight on the race in ohio. you all know how important ohio is. president obama holding a four-point lead in this new poll, slightly outside the margin of error and significantly right at the crucial 50% mark. so the question is, what is driving the numbers in ohio right now? chief national correspondent john king has some answers. >> well, anderson, that narrow ohio lead for the president is within the poll's sampling error but it is yet another poll showing the president with a small persistent lead in the state of ohio. let's take a closer look at why it is happening in this state that is so important in the pick for president. here's the main reason